Round trip delay between modems in T (1/2400 sec) units. Normally should be in the range of
100-200. A satellite link will introduce a delay of about 1300 T.
Xmitter Underrun
Number of times modem fails to provide data octet in time for transmission.
Receiver Overrun
Number of times modem fails to take data octet in time from receiver.
Last speed/protocol
The speed and protocol of the link before hang-up. It may be different from the initial speed
because of retrain and speed fall-back or fall-forward. Speed change is a clue of changing line
conditions.
Disconnect Reason
Possible reasons are
Local Hang up
Remote Hang up
Carrier Lost
On Line
Resent Expiration
Protocol Error
Break Timeout
DTR Dropped
Carrier Lost 1 (No handshaking response)
Carrier Lost 2 (Remote hang up, busy tone heard)
THROUGHPUT DISPLAY
If the modem is operated in asynchronous operation, we can tell the line quality from the
Throughput Display. If the speed displayed is slower than usual or what you expected, check the
S/N reading. If it is good, check the configuration of the modem and the PC serial port setting,
particularly the flow control setting, or even the configuration of the remote side.
RE-TRANSMISSION INDICATOR
In error control mode, an error occurring on the link will cause the data to be re-transmitted. At
the same time, the AA LED will flash. This is another way to know the quality of the line. On the
U-1496E, the EC LED will flash to indicate retransmission.
DIALING INDICATOR
On the U-1496E, the HS LED will flash 1 second on and 1 second off to indicate that the modem
is dialing.
